A major concern for immobile patients and like persons are medical conditions that form clots in the blood, such as, deep vein thrombosis (DVT) and peripheral edema. Such patients and persons include those undergoing surgery, anesthesia, extended periods of bed rest, etc. These blood clotting conditions generally occur in the deep veins of the lower extremities and/or pelvis. These veins, such as the iliac, femoral, popiteal and tibial return, deoxygenated blood to the heart. For example, when blood circulation in these veins is retarded due to illness, injury or inactivity, there is a tendency for blood to accumulate or pool. A static pool of blood may lead to the formation of a blood clot. A major risk associated with this condition is interference with cardiovascular circulation. Most seriously, a fragment of the blood clot can break loose and migrate. A pulmonary emboli can form from the fragment potentially blocking a main pulmonary artery, which may be life threatening. The current invention can also be applied to the treatment of other conditions, such as lymphedema.
The conditions and resulting risks associated with patient immobility may be controlled or alleviated by applying intermittent pressure to a patient's limb, such as, for example, a leg to assist in blood circulation. For example, sequential compression devices have been used, such as the device disclosed in U.S. Pat. No. 4,091,804 to Hasty. Sequential compression devices are typically constructed of two sheets of material secured together at the seams to define one or more fluid impervious bladders, which are connected to a source of pressure for applying sequential pressure around a patient's body parts for improving blood return to the heart. The inflatable sections are covered with a laminate to improve durability, patient comfort, and to protect against puncture. As part of the compression device, the two sheets are structurally designed to withstand a changing pressure over time under repeated use. Medical tubing is used to make connection of the source of pressure to the usually several bladders of the compression device. The source of air pressure is an air compressor most often located remotely from the patient.